Systems and methods for treating supraventricular arrhythmias

ABSTRACT

In various method embodiments, a supraventricular arrhythmia event is detected, and a supraventricular arrhythmia treatment, including neural stimulation to elicit a sympathetic response, is delivered in response to a detected supraventricular arrhythmia event. Some embodiments detect a precursor for a supraventricular arrhythmia episode, and deliver prophylactic neural stimulation to avoid the supraventricular arrhythmia event. Some embodiments detect a supraventricular arrhythmia episode, and deliver therapeutic neural stimulation for the supraventricular arrhythmia event.

CLAIM OF PRIORITY

This application is a division of and claims the benefit of priorityunder 35 U.S.C. §120 to U.S. patent application Ser. No. 11/677,116,filed on Feb. 21, 2007, which is hereby incorporated by reference hereinin its entirety.

FIELD

This application relates generally to medical devices and, moreparticularly, to systems, devices and methods for treatingsupraventricular arrhythmias,

BACKGROUND

The heart is the center of a person's circulatory system. The leftportions of the heart draw oxygenated blood from the lungs and pump itto the organs of the body to provide the organs with their metabolicneeds for oxygen. The right portions of the heart draw deoxygenatedblood from the body organs and pump it to the lungs where the blood getsoxygenated. Contractions of the myocardium provide these pumpingfunctions. In a normal heart, the sinoatrial node, the heart's naturalpacemaker, generates electrical impulses that propagate through anelectrical conduction system to various regions of the heart to excitethe myocardial tissues of these regions. Coordinated delays in thepropagations of the electrical impulses in a normal electricalconduction system cause the various portions of the heart to contract insynchrony, which efficiently pumps the blood. Blocked or abnormalelectrical conduction or deteriorated myocardial tissue causesdysynchronous contraction of the heart, resulting in poor hemodynamicperformance, including a diminished blood supply to the heart and therest of the body. Heart failure occurs when the heart fails to pumpenough blood to meet the body's metabolic needs.

Tachyarrhythmias are abnormal heart rhythms characterized by a rapidheart rate. Examples of tachyarrhythmias include supraventriculararrhythmias or supraventricular tachycardias (SVTs), and the moredangerous ventricular tachyarrhythmias which include ventriculartachycardia (VT) and ventricular fibrillation (VF). A supraventriculartachyarrhythmia (SVT) is an arrhythmia that originates from thesupraventricular region, such as the atrium, the sinus node, the AV nodeor AV junction. Examples of SVT include atrial tachyarrhythmia (AT) aswell as AV and AV Nodal Reentry Tachyarrhythmias (AVNRT). Atrialtachyarrhythmia includes atrial tachycardias such as atrial flutter, andfurther includes atrial fibrillation, for example. SVT can be conductedthrough the AV node, thus resulting in a ventricular tachyarrhythmiaassociated with the SVT, Thus, an atrial tachycardia can evolve intomore serious arrhythmias like ventricular tachycardia.

Some SVTs are chronic in nature, whereas others are not chronic. Theduration of these non-chronic SVTs can range from a time period of lessthan a minute to a time period of several days, An example of anon-chronic SVT is paroxysmal atrial tachycardia (PAT), which also maybe referred to as paroxysmal SVT, AVNRT or AV reentry tachycardia. PATis a type of rapid atrial arrhythmia characterized by brief periods ofsudden-onset and often abrupt termination of atrial tachycardia. Thesudden onset of the tachycardia is caused by micro-reentry within the AVnode or macro-reentry between the AV node and a bypass tract, and can beassociated with uncomfortable and annoying symptoms such aslightheadedness, chest pain, palpitations, anxiety, sweating andshortness of breath.

Cardioversion, an electrical shock delivered to the heart synchronouslywith the QRS complex, and defibrillation, an electrical shock deliveredwithout synchronization to the QRS complex, can be used to terminatemost tachyarrhythmias. The electric shock terminates the tachyarrhythmiaby simultaneously depolarizing the myocardium and rendering itrefractory. A class of cardiac rhythm management (CRM) devices known asan implantable cardioverter defibrillator (ICD) provides this kind oftherapy by delivering a shock pulse to the heart when the device detectstachyarrhythmias. Some SVTs, such as PAT, can be difficult to treatbecause it typically is not considered to be lethal enough to warrantdefibrillation shock treatment. Another type of electrical therapy fortachycardia is anti-tachycardia pacing (ATP). Modem ICDs typically haveATP capability, and deliver ATP therapy or a shock pulse when atachyarrhythmia is detected.

Cardioversion/defibrillation consumes a relatively large amount ofstored power from the battery and can cause patient discomfort. It isdesirable, therefore, to terminate a tachyarrhythmia whenever possiblewithout using shock therapy. Devices have therefore been programmed touse ATP to treat lower rate tachycardias and to usecardioversion/defibriliation shocks to terminate fibrillation andcertain high rate tachycardias.

SUMMARY

Various device embodiments comprise a controller, a sensor, and a neuralstimulator. The sensor is adapted to cooperate with the controller todetect a supraventricular arrhythmia event. The neural stimulator isadapted to stimulate a neural target to elicit a sympathetic response.The controller is adapted to control the neural stimulator to stimulatethe neural target in response to the detected supraventriculararrhythmia event.

Various system embodiments comprise means for detecting asupraventricular arrhythmia event, and means for delivering asupraventricular arrhythmia treatment in response to a detectedsupraventricular arrhythmia event. The means for delivering asupraventricular arrhythmia treatment includes means for deliveringneural stimulation to elicit a sympathetic response.

In various method embodiments, a supraventricular arrhythmia event isdetected, and a supraventricular arrhythmia treatment, including neuralstimulation to elicit a sympathetic response, is delivered in responseto a detected supraventricular arrhythmia event. Some embodiments detecta precursor for a supraventricular arrhythmia episode, and deliverprophylactic neural stimulation in avoid the supraventricular arrhythmiaevent. Some embodiments detect a supraventricular arrhythmia episode,and deliver therapeutic neural stimulation for the supraventriculararrhythmia event.

This Summary is an overview of some of the teachings of the presentapplication and not intended to be an exclusive or exhaustive treatmentof the present subject matter. Further details about the present subjectmatter are found in the detailed description and appended claims. Otheraspects will be apparent to persons skilled in the art upon reading andunderstanding the following detailed description and viewing thedrawings that form a part thereof, each of which are not to be taken ina limiting sense, The scope of the present invention is defined by theappended claims and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment of an atrial arrhythmia therapy.

FIG. 2 illustrates neural stimulation therapy for atrial arrhythmias inconjunction with one or more other atrial therapies, according tovarious embodiments.

FIG. 3 illustrates a heart and anatomical features in a cervical region,including the left and right vagus nerves, the left and right carotidarteries, and the left and right internal jugular veins.

FIG. 4 illustrates an embodiment of a neural stimulator that stimulatessympathetic activity in a cardiac sympathetic nerve.

FIG. 5 illustrates a neural stimulator with a lead extending to thecardiac sympathetic nerve and to the vagus nerve.

FIG. 6 illustrates sympathetic ganglion proximate to the brachiocephalicor innominate veins, the internal jugular veins and subclavian veins.

FIG. 7 illustrates a transluminal neural stimulation using electrodeswithin the lumen, according to various embodiments.

FIG. 8 illustrates a system embodiment in which an IMD is placedsubcutaneously or submuscularly in a patient's chest with lead(s)positioned to stimulate a vagus nerve.

FIG. 9 illustrates a system embodiment that includes an implantablemedical device (IMD) with satellite electrode(s) positioned to stimulateat least one neural target.

FIG. 10 illustrates an implantable medical device (IMD), according tovarious embodiments of the present subject matter.

FIG. 11 is a block diagram illustrating an embodiment of an externalsystem,

FIG. 12 illustrates an IMD placed subcutaneously or submuscularly in apatient's chest with lead(s) positioned to provide a CRM therapy to aheart, and with lead(s) positioned to stimulate and/or inhibit neuraltraffic at a cervical neural target, according to various embodiments.

FIG. 13 illustrates an IMD with lead(s) positioned to provide a CRMtherapy to a heart, and with satellite transducers positioned tostimulate/inhibit a cervical neural target, according to variousembodiments.

FIG. 14 illustrates an implantable medical device (IMD) having a neuralstimulation (NS) component and a cardiac rhythm management (CRM)component according to various embodiments of the present subjectmatter.

FIG. 15 shows a system diagram of an embodiment of amicroprocessor-based implantable device, according to variousembodiments.

DETAILED DESCRIPTION

The following detailed description of the present subject matter refersto the accompanying drawings which show, by way of illustration,specific aspects and embodiments in which the present subject matter maybe practiced. These embodiments are described in sufficient detail toenable those skilled in the art to practice the present subject matter.Other embodiments may be utilized and structural, logical, andelectrical changes may be made without departing from the scope of thepresent subject matter. References to “an”, “one”, or “various”embodiments in this disclosure are not necessarily to the sameembodiment, and such references contemplate more than one embodiment.The following detailed description is, therefore, not to be taken in alimiting sense, and the scope is defined only by the appended claims,along with the full scope of legal equivalents to which such claims areentitled.

Heart rate and force is increased when the sympathetic nervous system isstimulated, and is decreased when the sympathetic nervous system isinhibited (the parasympathetic nervous system is stimulated). Cardiacrate, contractility, and excitability are known to be modulated bycentrally mediated reflex pathways, Baroreceptors and chemoreceptors inthe heart, great vessels, and lungs, transmit cardiac activity throughparasympathetic and sympathetic afferent fibers to the central nervoussystem. Activation of sympathetic afferents triggers reflex sympatheticactivation, vasoconstriction, and tachycardia. In contrast,parasympathetic activation results in bradycardia, vasodilation,sympathetic inhibition, and inhibition of vasopressin release.

Neural stimulation can be used to stimulate nerve traffic or inhibitnerve traffic. An example of neural stimulation to stimulate nervetraffic is a lower frequency stimulation signal (e.g. within a range onthe order of 20 Hz to 50 Hz). An example of neural stimulation toinhibit nerve traffic is a higher frequency stimulation signal (e.g.within a range on the order of 120 Hz to 150 Hz). Other methods forstimulating and inhibiting nerve traffic have been proposed, includingmodal block of nerve traffic.

High-amplitude vagal (parasympathetic) stimulation appears to beatrially proarrhythmic; and both sympathetic stimulation andlow-amplitude vagal stimulation appear to be atrially anti-arrhythmic.Sympathetic stimulation or parasympathetic inhibition alters theelectrophysiologic properties of the atria, prolonging the atrialrefractory period and decreasing the rate of atrial tachyarrhythmias.The present subject matter provides a therapy for atrial arrhythmiasthat uses sympathetic stimulation and/or parasympathetic inhibition tosuppress or convert supraventricular arrhythmias. The anti-arrhythmicmechanism may be due to one or more of an increase in atrial refractoryperiod, a reduction in anisotropy, or a reduction of ectopic beats.

Various embodiments detect a supraventricular arrhythmia, such as atrialfibrillation and atrial flutter, and deliver neural stimulation inresponse to the detected supraventricular arrhythmia to elicit asympathetic response. The sympathetic response can be elicited bystimulating a sympathetic nerve target, inhibiting a parasympatheticnerve target, or both stimulating a sympathetic nerve target andinhibiting a parasympathetic nerve target. According to variousembodiments, a neural stimulator uses a neural stimulation element suchas nerve cuff electrodes and intravascularly-fed electrodes totransvascularly stimulate a neural target. According to variousembodiments, the neural stimulation element includes a transduceradapted to deliver ultrasound energy, a transducer adapted to deliverlight energy, a transducer adapted to deliver magnetic energy, or atransducer adapted to deliver thermal energy.

In order to elicit a sympathetic response by stimulation of asympathetic nerve target, some embodiments stimulate sympatheticganglion, and some embodiments stimulate a cardiac sympathetic nerve. Inorder to elicit a sympathetic response by inhibiting parasympatheticnerve traffic, some embodiments inhibit parasympathetic traffic in thevagus nerve or a branch thereof. Some embodiments inhibit vagal nerveactivity by applying a low amplitude parasympathetic stimulation of thevagus nerve. Other ways for inhibiting parasympathetic nerve traffic canbe used, such as inhibiting neural activity in parasympathetic neuraltargets such as baroreceptors and cardiac fat pads.

According to various embodiments, the supraventricular arrhythmia isdetected using electrodes such as subcutaneous electrodes integratedinto the pulse generator or electrodes on one or more intracardiacleads. The atrial arrhythmia may be able to be detected using an atrialelectrogram, or with existing cardiac rhythm management (CRM)supraventricular discrimination algorithms. For example, implantablecardiac defibrillators can apply a supraventricular tachycardiadiscrimination algorithm to determine whether ventricular activityoriginates in the ventricles and can be treated with a ventricular shockor if the ventricular activity is caused by a supraventriculartachycardia. However, in the present subject matter, thesupraventricular tachycardia is detected before the therapy for thesupraventricular tachycardia is delivered. Morphology and stability canbe used to determine if a supraventricular tachycardia is present. TheQRS waveform pattern for a ventricular tachycardia is different from theQRS waveform pattern for a supraventricular tachycardia is different.The ORS wave is narrower for the supraventricular tachycardia. Stabilityrefers to the rate stability of the tachyarrhythmia. Steadierventricular rates typically indicate a supraventricular arrhythmia, andmore irregular ventricular rates typically indicate a ventriculartachyarrhythmia. A sensing electrode in the atria can be used to providean atrial electrogram for detecting an atrial tachyarrhythmia. A sensinglead in the ventricle can be used, in conjunction with discriminationalgorithms, to determine if the ventricular activity is attributable toa supraventricular tachyarrhythmia. ECG electrodes, such as may beplaced on the can of the implantable device, can be used in conjunctionwith discrimination algorithms to identify QRS waveforms attributable toa supraventricular tachyarrhythmia.

Various embodiments provide neural stimulation therapy for atrialarrhythmias in conjunction with one or more other atrial therapies, suchas anti-tachycardia pacing, low-energy cardioversion, anti-arrhythmiashocks, and drug delivery. The neural stimulation therapy and any ofthese other therapies may be applied simultaneously, in a synchronizedfashion, or in a tiered fashion.

As a prolonged sympathetic response is undesirable, temporary neuralstimulation to elicit the sympathetic response is provided in responseto a detected supraventricular arrhythmia, or a detectedsupraventricular precursor to a supraventricular arrhythmia. Forexample, the neural stimulation may be temporarily delivered for aduration of seconds to minutes. An embodiment, for example, provides theneural stimulation in response to a detected supraventricular arrhythmiafor a duration within a range between ten seconds to two minutes. Theduration is not necessarily limited to the ten second to two minuterange.

Some embodiments place a lead in a vessel near the stellate ganglion totransvascularly stimulate the stellate ganglion. Some embodiments placea cuff or proximate lead to the stellate ganglion for use in stimulatingthe stellate ganglion. Some embodiments place a lead on or near thecervical sympathetic trunk; and some embodiments place a lead on or nearthe cervical vagus nerve. Some embodiments access both the cervicalsympathetic trunk and the cervical vagus nerve to permit bothsympathetic stimulation and to also permit parasympathetic sensingand/or stimulation. Some embodiments use a combination or bifurcatedlead to access both the cervical sympathetic trunk and the cervicalvagus nerve.

FIG. 1 illustrates an embodiment of an atrial arrhythmia therapy. In theillustrated embodiment, a supraventricular arrhythmia is detected at101. The supraventricular arrhythmia may be an atrial flutter or anatrial fibrillation, for example. At 101, various embodiments search forand detect a specific supraventricular arrhythmia that is amenable toneural stimulation treatment that elicits a sympathetic response. Aprecursor for a supraventricular arrhythmia may be detected at 101, anda prophylactic therapy may be applied in response. The supraventricularcan be detected using an atrial electrogram or using various knowndiscrimination algorithms. If a supraventricular arrhythmia is detected,the process proceeds to 102, where neural stimulation is delivered toelicit a sympathetic response, through stimulation of a sympatheticneural target and/or inhibition of a parasympathetic neural target. Theneural stimulation is delivered to suppress or convert supraventriculararrhythmias.

The process illustrated in FIG. 1 illustrates a detectedsupraventricular arrhythmia. The decision at 101 can be whether asupraventricular arrhythmia event has occurred, where a supraventriculararrhythmia event may include a precursor of a supraventriculararrhythmia episode or the supraventricular arrhythmia episode itself.The neural stimulation to elicit a sympathetic response, illustrated at102, is a supraventricular arrhythmia treatment, which may include aprophylactic treatment for supraventricular arrhythmia in response to adetected precursor, or a therapeutic treatment for a detected episode ofsupraventricular arrhythmia.

FIG. 2 illustrates neural stimulation therapy for atrial arrhythmias inconjunction with one or more other atrial therapies, according tovarious embodiments. At 201, it is determined whether there is asupraventricular arrhythmia for which a therapy wilt be delivered. Ifsuch a supraventricular arrhythmia is detected, the process proceeds to203 to deliver a therapy for the detected supraventricular arrhythmia.The therapy delivered at 203 includes delivering neural stimulation toelicit a sympathetic response, as illustrated at 202. According tovarious embodiments, the therapy delivered at 203 also includesdelivering antitachycardia pacing at 204. According to variousembodiments, the therapy delivered at 203 also includes delivering anantitachycardia shock at 205. According to various embodiments, thetherapy delivered at 203 also includes delivering antiarrhythmia drugtherapy at 206. Some embodiments include various combinations of two ormore of these other therapies 204, 205, and/or 206. Any of these othertherapies 204, 205, and/or 206 may be applied simultaneously, in asynchronized fashion, or in a tiered fashion with the neuralstimulation.

By way of example and not limitation, various embodiments respond to adetected supraventricular arrhythmia by delivering neural stimulation.If the neural stimulation does not suppress or convert thesupraventricular arrhythmia, an antitachycardia pacing (ATP) isdelivered, followed by an antitachycardia shock if the ATP is notsuccessful in suppressing or converting the supraventricular arrhythmia.Some embodiments terminate the neural stimulation before delivering theATP, and some embodiments deliver the neural stimulation simultaneouslywith the neural stimulation. In embodiments that deliver the neuralstimulation simultaneously with the neural stimulation, some embodimentsdeliver the neural stimulation first, and then add ATP therapy inaddition to the neural stimulation, and some embodiments initiallyprovide the combination of neural stimulation and ATP in response to thedetected supraventricular arrhythmia. The particular scheme used fortreating the arrhythmia can be preset or can be programmed by aphysician.

FIG. 3 illustrates a heart 307 and anatomical features in a cervicalregion, including the left and right vagus nerves 308 and 309, the leftand right carotid arteries 310 and 311, and the left and right internaljugular veins 312 and 313. Also illustrated in FIG. 3 are the trachea314, pulmonary artery 315, aorta 316, superior vena cava 317, the leftand right innominate veins 318 and 319 (also referred to asbrachiocephalic veins), and the left and right subclavian veins 320 and321. Some embodiments transvascularly stimulate a desired neural target.Those of ordinary skill in the art, upon reading and comprehending thisdisclosure, would understand how to transvascularly stimulate the neuraltarget using vessels such as the innominate, subclavian and internaljugular veins to access the neural target.

FIG. 4 illustrates an embodiment of a neural stimulator that stimulatessympathetic activity in a cardiac sympathetic nerve. FIG. 4 illustratesportions of a common carotid artery 411, the internal jugular vein 413,the subclavian vein 421 and the vagus nerve 409. The figure alsoillustrates portions of the subclavian artery 422, the clavicle 423 andthe sympathetic nerve trunk 424. In the embodiment illustrated in FIG.4, an implantable neural stimulator 425 includes a stimulation lead witha nerve cuff electrode positioned to stimulate the cardiac sympatheticnerve trunk 424 as part of the therapy for a supraventriculararrhythmia.

FIG. 5 illustrates a neural stimulator 525 with a lead extending to thecardiac sympathetic nerve 524 and to the vagus nerve 509. A sympatheticresponse can be elicited by inhibiting nerve traffic on the vagus nerveand/or stimulating nerve traffic on the cardiac sympathetic nerve.Various embodiments use a sensor to detect nerve traffic at one of theneural locations to control stimulation at the other neural location.For example, one embodiment stimulates the cardiac sympathetic nerve toprovide the sympathetic response, and uses vagus nerve activity asfeedback to control the neural stimulation of the cardiac sympatheticnerve. Other neural locations can be used in addition to or in place ofone or both of the neural locations illustrated in FIG. 5. Also,separate leads can be used, or a bifurcated lead can be used to accessthe neural locations.

FIG, 6 illustrates sympathetic ganglion 626 proximate to thebrachiocephalic or innominate veins 618 and 619, the internal jugularveins 612 and 613 and the subclavian veins 620 and 621. The left andright brachiocephalic veins are formed by the union of eachcorresponding internal jugular vein and subclavian vein. Sympatheticganglion are formed along the sympathetic nerve trunk. Those of ordinaryskill in the art, upon reading and comprehending this disclosure, wouldunderstand how to transvascularly stimulate a neural target usingvessels such as the innominate, subclavian and internal jugular veins toaccess the neural target. Those of ordinary skill in the art would alsobe able to account for anatomical variations in the respective positionsof the veins and neural targets. For example, the stellate ganglion,illustrated as the lower two ganglion 626 in the figure, can betransvascularly stimulated through a vein such as the subclavian orinnominate veins. The vagus nerve, such as illustrated in FIG. 5, canalso be transvascularly stimulated from the internal jugular vein. In abifurcated lead embodiment, by way of example and not limitation, onebranch of the lead is ted into the internal jugular vein to access avagus nerve, and the other branch of the lead is fed into the subclavianvein. If the stellate ganglion is capable of being stimulated from theinnominate vein, a single, combination lead can be fed through theinnominate vein for use in stimulating the stellate ganglion, and thenfurther fed into the internal jugular vein for use in stimulating thevagus nerve and/or sensing neural traffic on the vagus nerve.

FIG. 7 illustrates a transluminal neural stimulation using electrodeswithin a lumen or vasculature, according to various embodiments. Thefigure illustrates a lumen 727 (e.g. subclavian, internal jugular, orinnominate veins), a nerve 728 or ganglion external to the lumen, and alead 729 within the lumen. The neural stimulation generates anelectrical field 730 between electrodes 731. The electric field extendspast the lumen wall to the nerve.

FIG. 8 illustrates a system embodiment in which an implantable medicaldevice (IMD) 832 is placed subcutaneously or submuscularly in apatient's chest with lead(s) 833 positioned to stimulate a neural targetin the cervical region (e.g. a vagus nerve or cardiac sympatheticnerve). According to various embodiments, neural stimulation lead(s) 833are subcutaneously tunneled to a neural target, and can have a nervecuff electrode to stimulate the neural target. Some vagus nervestimulation lead embodiments are intravascularly fed into a vesselproximate to the neural target, and use electrode(s) within the vesselto transvascularly stimulate the neural target. For example, someembodiments stimulate the vagus using electrode(s) positioned within theinternal jugular vein, and stimulate the stellate ganglion usingelectrode(s) positioned within the subclavian and/or innominate veins.The neural targets can be stimulated using other energy waveforms, suchas ultrasound and light energy waveforms. Other neural targets can bestimulated, such as cardiac nerves and cardiac fat pads. The illustratedsystem includes leadless ECU electrodes on the housing of the device.These ECG electrodes 834 are capable of being used to detect heart rate,for example.

FIG. 9 illustrates a system embodiment that includes an implantablemedical device (IMD) 932 with satellite electrode(s) 933 positioned tostimulate at least one cervical neural target (e.g. vagus nerve, cardiacsympathetic nerve, and stellate ganglion). The satellite electrode(s)are connected to the IMD, which functions as the planet for thesatellites, via a wireless link. Stimulation and communication can beperformed through the wireless link. Examples of wireless links includeRF links and ultrasound links. Examples of satellite electrodes includesubcutaneous electrodes, nerve cuff electrodes and intravascularelectrodes. Various embodiments include satellite neural stimulationtransducers used to generate neural stimulation waveforms such asultrasound and light waveforms. The illustrated system includes leadlessECG electrodes on the housing of the device. These ECG electrodes 934are capable of being used to detect heart rate, for example.

FIG. 10 illustrates an implantable medical device (IMD) 1032, accordingto various embodiments of the present subject matter. The illustratedIMD 1032 provides neural stimulation signals for delivery topredetermined neural targets to provide supraventricular arrhythmiatherapy using an elicited neural stimulation response. The illustrateddevice includes controller circuitry 1033 and memory 1034. Thecontroller circuitry is capable of being implemented using hardware,software, and combinations of hardware and software. For example,according to various embodiments, the controller circuitry includes aprocessor to perform instructions embedded in the memory to performfunctions associated with the neural stimulation therapy. Theillustrated device further includes a transceiver 1035 and associatedcircuitry for use to communicate with a programmer or another externalor internal device. Various embodiments have wireless communicationcapabilities. For example, some transceiver embodiments use a telemetrycoil to wirelessly communicate with a programmer or another external orinternal device.

The illustrated device further includes a therapy delivery system 1036,such as neural stimulation circuitry. Other therapy delivery systems,such as drug delivery systems, can be also used. The illustrated devicealso includes sensor circuitry 1037. The sensor circuitry can be used todetect a supraventricular arrhythmia to trigger the therapy delivery.Some embodiments uses sensor circuitry adapted to detect nerve trafficfor use in providing neural stimulation control feedback. Otherphysiological parameters, such as heart rate, respiration, and bloodpressure can be sensed to provide neural stimulation control feedback.According to some embodiments, one or more leads are able to beconnected to the sensor circuitry and neural stimulation circuitry. Someembodiments use wireless connections between the sensor(s) and sensorcircuitry, and some embodiments use wireless connections between thestimulator circuitry and electrodes. According to various embodiments,the neural stimulation circuitry is used to apply electrical stimulationpulses to desired neural targets, such as through one or morestimulation electrodes 1038 positioned at predetermined location(s).Some embodiments use transducers to provide other types of energy, suchas ultrasound, light or magnetic energy. The controller circuitry cancontrol the therapy provided by system using a therapy schedule inmemory 1034, or can compare a target range (or ranges) of the sensedphysiological response(s) stored in the memory 1034 to the sensedphysiological response(s) to appropriately adjust the intensity of theneural stimulation/inhibition, The target range(s) can be programmable.

According to various embodiments using neural stimulation, thestimulation circuitry 1036 is adapted to set or adjust any one or anycombination of stimulation features. Examples of stimulation featuresinclude the amplitude, frequency, polarity and wave morphology of thestimulation signal. Examples of wave morphology include a square wave,triangle wave, sinusoidal wave, and waves with desired harmoniccomponents to mimic white noise such as is indicative ofnaturally-occurring baroreflex stimulation. Some embodiments of theneural stimulation circuitry are adapted to generate a stimulationsignal with a predetermined amplitude, morphology, pulse width andpolarity, and are further adapted to respond to a control signal fromthe controller to modify at least one of the amplitude, wave morphology,pulse width and polarity. Some embodiments of the neural stimulationcircuitry are adapted to generate a stimulation signal with apredetermined frequency, and are further adapted to respond to a controlsignal from the controller to modify the frequency of the stimulationsignal.

The controller 1033 can be programmed to control the neural stimulationdelivered by the stimulation circuitry 1036 according to stimulationinstructions, such as a stimulation schedule, stored in the memory 1034.Neural stimulation can be delivered in a stimulation burst, which is atrain of stimulation pulses at a predetermined frequency. Stimulationbursts can be characterized by burst durations and burst intervals. Aburst duration is the length of time that a burst lasts. A burstinterval can be identified by the time between the start of successivebursts. A programmed pattern of bursts can include any combination ofburst durations and burst intervals. A simple burst pattern with oneburst duration and burst interval can continue periodically for aprogrammed period or can follow a more complicated schedule. Theprogrammed pattern of bursts can be more complicated, composed ofmultiple burst durations and burst interval sequences. The programmedpattern of bursts can be characterized by a duty cycle, which refers toa repeating cycle of neural stimulation ON for a fixed time and neuralstimulation OFF for a fixed time.

According to some embodiments, the controller 1033 controls the neuralstimulation generated by the stimulation circuitry by initiating eachpulse of the stimulation signal. In some embodiments, the controllercircuitry initiates a stimulation signal pulse train, where thestimulation signal responds to a command from the controller circuitryby generating a train of pulses at a predetermined frequency and burstduration. The predetermined frequency and burst duration of the pulsetrain can be programmable. The pattern of pulses in the pulse train canbe a simple burst pattern with one burst duration and burst interval orcan follow a more complicated burst pattern with multiple burstdurations and burst intervals. In sonic embodiments, the controller 1033controls the stimulation circuitry 1036 to initiate a neural stimulationsession and to terminate the neural stimulation session. The burstduration of the neural stimulation session under the control of thecontroller 1033 can be programmable. The controller may also terminate aneural stimulation session in response to an interrupt signal, such asmay be generated by one or more sensed parameters or any other conditionwhere it is determined to be desirable to stop neural stimulation.

The illustrated device includes a clock or timer 1039 which can be usedto execute the programmable stimulation schedule. For example, aphysician can program a daily schedule of therapy based on the time ofday if the detected supraventricular arrhythmia if the severity of thearrhythmia is such that therapy can wait until a more convenient timefor the patient. A stimulation session can begin at a first programmedtime, and can end at a second programmed time. Various embodimentsinitiate and/or terminate a stimulation session based on a signaltriggered by a user. Various embodiments use sensed data to enableand/or disable a stimulation session. Thus, for example, the dock can beused to provide an enabling condition for the therapy in addition to adetected supraventricular arrhythmia event By way of another example ofa two or more conditions functioning together to enable a therapy, anactivity sensor and the supraventricular arrhythmia detector canfunction together to provide supraventricular arrhythmia treatment onlyduring periods of lower activity, as determined by a detected activitybelow an activity threshold.

According to various embodiments, the schedule refers to the timeintervals or period when the neural stimulation therapy is delivered. Aschedule can be defined by a start time and an end time, or a start timeand a duration. Various device embodiments apply the therapy accordingto the programmed schedule contingent on enabling conditions in additionto a detected supraventricular arrhythmia, such as patient rest orsleep, tow heart rate levels, time of day, and the like. The therapyschedule can also specify how the stimulation is delivered, such ascontinuously at the pulse frequency throughout the identified therapyperiod (e.g. 5 Hz pulse frequency for two minutes), or according to adefined duty cycle during the therapy delivery period (e.g. 10 secondsper minute at 5 Hz pulse frequency for two minutes). As illustrated bythese examples, the therapy schedule is distinguishable from the dutycycle.

FIG. 11 is a block diagram illustrating an embodiment of an externalsystem 1140. The external system includes a programmer, in someembodiments. In the illustrated embodiment, the external system includesa patient management system. As illustrated, the external system 1140 isa patient management system including an external device 1141, atelecommunication network 1142, and a remote device 1143. Externaldevice 1141 is placed within the vicinity of an implantable medicaldevice (IMD) and includes external telemetry system 1144 to communicatewith the IMD. Remote device(s) 1143 is in one or more remote locationsand communicates with external device 1141 through network 1142, thusallowing a physician or other caregiver to monitor and treat a patientfrom a distant location and/or allowing access to various treatmentresources from the one or more remote locations. The illustrated remotedevice 1143 includes a user interface 1145. According to variousembodiments, the external device includes a programmer or other devicesuch as a computer, a personal data assistant or phone. The externaldevice 1141, in various embodiments, includes two devices adapted tocommunicate with each other over an appropriate communication channel,such as a computer and a Bluetooth enabled portable device (e.g.personal digital assistant, phone), by way of example and notlimitation.

FIG. 12 illus rates an IMD 123 placed subcutaneously or submuscularly apatient's chest with lead(s) 1246 positioned to provide a CRM therapy toa heart, and with lead(s) 1233 positioned to stimulate and/or inhibitneural traffic at a cervical neural target, according to variousembodiments. According to various embodiments, neural stimulationlead(s) are subcutaneously tunneled to a neural target, and can have anerve cuff electrode to stimulate the neural target. Some leadembodiments are intravascularly fed into a vessel proximate to theneural target, and use transducer(s) within the vessel totransvascularly stimulate the neural target. For example, someembodiments target the vagus nerve using electrode(s) positioned withinthe internal jugular vein and some embodiments stimulate the stellateganglion using electrode(s) positioned within the subclavian and/orinnominate veins.

FIG. 13 illustrates an IMD 1332 with lead(s) 1346 positioned to providea CRM therapy to ahead, and with satellite transducers 1333 positionedto stimulate/inhibit a cervical neural target, according to variousembodiments. The satellite transducers are connected to the IMD, whichfunctions as the planet for the satellites, via a wireless link.Stimulation and communication can be performed through the wirelesslink. Examples of wireless links include RF links and ultrasound links.Although not illustrated, some embodiments perform myocardialstimulation using wireless links. Examples of satellite transducersinclude subcutaneous electrodes, nerve cuff electrodes and intravascularelectrodes.

FIG. 14 illustrates an implantable medical device (IMD) 1447 having aneural stimulation (NS) component 1448 and a cardiac rhythm management(CRM) component 1449 according to various embodiments of the presentsubject matter. The illustrated device includes a controller 1450 andmemory 1451. According to various embodiments, the controller includeshardware, software, or a combination of hardware and software to performthe neural stimulation and CRM functions. For example, the programmedtherapy applications discussed in this disclosure are capable of beingstored as computer-readable instructions embodied in memory and executedby a processor. For example, therapy schedule(s) and programmableparameters can be stored in memory. According to various embodiments,the controller includes a processor to execute instructions embedded inmemory to perform the neural stimulation and CRM functions. Theillustrated neural stimulation therapy 1452 includes an supraventriculararrhythmia therapy. Various embodiments include CRM therapies 1453, suchas bradycardia pacing, anti-tachycardia therapies such as ATP,defibrillation and cardioversion, and cardiac resynchronization therapy(CRT). The illustrated device further includes a transceiver 1454 andassociated circuitry for use to communicate with a programmer or anotherexternal or internal device. Various embodiments include a telemetrycoil.

The CRM therapy section 1449 includes components, under the control ofthe controller, to stimulate a heart and/or sense cardiac signals usingone or more electrodes. The illustrated CRM therapy section includes apulse generator 1455 for use to provide an electrical signal through anelectrode to stimulate a heart, and further includes sense circuitry1456 to detect and process sensed cardiac signals. An interface 1457 isgenerally illustrated for use to communicate between the controller 1450and the pulse generator 1455 and sense circuitry 1456. Three electrodesare illustrated as an example for use to provide CRM therapy. However,the present subject matter is not limited to a particular number ofelectrode sites. Each electrode may include its own pulse generator andsense circuitry. However, the present subject matter is not so limited.The pulse generating and sensing functions can be multiplexed tofunction with multiple electrodes.

The INS therapy section 1448 includes components, under the control ofthe controller, to stimulate a neural stimulation target and/or senseparameters associated with nerve activity or surrogates of nerveactivity such as heart rate, blood pressure and respiration. Threeinterfaces 1458 are illustrated for use to provide neural stimulation.However, the present subject matter is not limited to a particularnumber interfaces, or to any particular stimulating or sensingfunctions. Pulse generators 1459 are used to provide electrical pulsesto transducer or transducers for use to stimulate a neural stimulationtarget. According to various embodiments, the pulse generator includescircuitry to set, and in some embodiments change, the amplitude of thestimulation pulse, the frequency of the stimulation pulse, the burstfrequency of the pulse, and the morphology of the pulse such as a squarewave, triangle wave, sinusoidal wave, and waves with desired harmoniccomponents to mimic white noise or other signals. Sense circuits 1460are used to detect and process signals from a sensor, such as a sensorof nerve activity, heart rate, blood pressure, respiration, and thelike. The interfaces 1158 are generally illustrated for use tocommunicate between the controller 1450 and the pulse generator 1459 andsense circuitry 1460. Each interface, for example, may be used tocontrol a separate lead. Various embodiments of the NS therapy sectiononly includes a pulse generator to stimulate a neural target. Theillustrated device further includes a clock/timer 1461, which can beused to deliver the programmed therapy according to a programmedstimulation protocol and/or schedule.

FIG. 15 shows a system diagram of an embodiment of amicroprocessor-based implantable device, according to variousembodiments. The controller of the device is a microprocessor 1562 whichcommunicates with a memory 1563 via a bidirectional data bus. Thecontroller could be implemented by other types of logic circuitry (e.g.,discrete components or programmable logic arrays) using a state machinetype of design. As used herein, the term “circuitry” should be taken torefer to either discrete logic circuitry or to the programming of amicroprocessor. Shown in the figure are three examples of sensing andpacing channels designated “A” through “C” comprising bipolar leads withring electrodes 1564A-C and tip electrodes 1565A-C, sensing amplifiers1566A-C, pulse generators 1567A-C, and channel interfaces 1568A-C, Eachchannel thus includes a pacing channel made up of the pulse generatorconnected to the electrode and a sensing channel made up of the senseamplifier connected to the electrode. The channel interfaces 1568A-Ccommunicate bidirectionally with the microprocessor 1562, and eachinterface may include analog-to-digital converters for digitizingsensing signal inputs from the sensing amplifiers and registers that canbe written to by the microprocessor in order to output pacing pulses,change the pacing pulse amplitude, and adjust the gain and thresholdvalues for the sensing amplifiers. The sensing circuitry of thepacemaker detects a chamber sense, either an atrial sense or ventricularsense, when an electrogram signal (i.e., a voltage sensed by anelectrode representing cardiac electrical activity) generated by aparticular channel exceeds a specified detection threshold. Pacingalgorithms used in particular pacing modes employ such senses to triggeror inhibit pacing. The intrinsic atrial and/or ventricular rates can bemeasured by measuring the time intervals between atrial and ventricularsenses, respectively, and used to detect atrial and ventriculartachyarrhythmias.

The electrodes of each bipolar lead are connected via conductors withinthe lead to a switching network 1569 controlled by the microprocessor.The switching network is used to switch the electrodes to the input of asense amplifier in order to detect intrinsic cardiac activity and to theoutput of a pulse generator in order to deliver a pacing pulse. Theswitching network also enables the device to sense or pace either in abipolar mode using both the ring and tip electrodes of a lead or in aunipolar mode using only one of the electrodes of the lead with thedevice housing (can) 1570 or an electrode on another lead serving as aground electrode. A shock pulse generator 1571 is also interfaced to thecontroller for delivering a defibrillation shock via a pair of shockelectrodes 1572 and 1573 upon detection of a shockable tachyarrhythmia.

Neural stimulation channels, identified as channels D and E, areincorporated into the device for delivering parasympathetic stimulationand/or sympathetic inhibition, where one channel includes a bipolar leadwith a first electrode 1574D and a second electrode 1575D, a pulsegenerator 1576D, and a channel interface 1577D, and the other channelincludes a bipolar lead with a first electrode 1574E and a secondelectrode 1575E, a pulse generator 1576E, and a channel interface 1577E.Other embodiments may use unipolar leads in which case the neuralstimulation pulses are referenced to the can or another electrode. Thepulse generator for each channel outputs a train of neural stimulationpulses which may be varied by the controller as to amplitude, frequency,duty-cycle, and the like. In this embodiment, each of the neuralstimulation channels uses a lead which can be intravascularly disposednear an appropriate neural target. Other types of leads and/orelectrodes may also be employed. A nerve cuff electrode may be used inplace of an intravascularly disposed electrode to provide neuralstimulation. In some embodiments, the leads of the neural stimulationelectrodes are replaced by wireless links.

The figure illustrates a telemetry interface 1578 connected to themicroprocessor, which can be used to communicate with an externaldevice. The illustrated microprocessor 1562 is capable of performingneural stimulation therapy routines and myocardial (CRM) stimulationroutines. Examples of NS therapy routines include a supraventriculararrhythmia therapy that uses neural stimulation that elicits asympathetic response. Examples of myocardial therapy routines includebradycardia pacing therapies, anti-tachycardia shock therapies such ascardioversion or defibrillation therapies, anti-tachycardia pacingtherapies (ATP), and cardiac resynchronization therapies (CRT).

According to various embodiments, the device, as illustrated anddescribed above, is adapted to deliver neural stimulation as electricalstimulation to desired neural targets, such as through one or morestimulation electrodes positioned at predetermined location(s). Otherelements for delivering neural stimulation can be used. For example,some embodiments use transducers to deliver neural stimulation usingother types of energy, such as ultrasound, light, magnetic or thermalenergy.

One of ordinary skill in the art will understand that, the modules andother circuitry shown and described herein can be implemented usingsoftware, hardware, and combinations of software and hardware. As such,the terms module and circuitry are intended to encompass softwareimplementations, hardware implementations, and software and hardwareimplementations.

The methods illustrated in this disclosure are not intended to beexclusive of other methods within the scope of the present subjectmatter. Those of ordinary skill in the art will understand, upon readingand comprehending this disclosure, other methods within the scope of thepresent subject matter. The above-identified embodiments, and portionsof the illustrated embodiments, are not necessarily mutually exclusive.These embodiments, or portions thereof can be combined. In variousembodiments, the methods are implemented using a computer data signalembodied in a carrier wave or propagated signal, that represents asequence of instructions which, when executed by a processor cause theprocessor to perform the respective method. In various embodiments, themethods are implemented as a set of instructions contained on acomputer-accessible medium capable of directing a processor to performthe respective method. In various embodiments, the medium is a magneticmedium, an electronic medium, or an optical medium.

It is to be understood that the above detailed description is intendedto be illustrative, and not restrictive. Other embodiments will beapparent to those of skill in the art upon reading and understanding theabove description. The scope of the invention should, therefore, bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled.

1. A method, comprising: detecting a supraventricular arrhythmia event;and delivering a supraventricular arrhythmia treatment in response to adetected supraventricular arrhythmia event, including delivering neuralstimulation to elicit a sympathetic response.
 2. The method of claim 1,wherein: detecting a supraventricular arrhythmia event includesdetecting a precursor for a supraventricular arrhythmia episode; anddelivering neural stimulation to elicit a sympathetic response includesdelivering prophylactic neural stimulation to avoid the supraventriculararrhythmia event.
 3. The method of claim 1, wherein: detecting asupraventricular arrhythmia event includes detecting a supraventriculararrhythmia episode; and delivering neural stimulation to elicit asympathetic response includes delivering therapeutic neural stimulationfor the supraventricular arrhythmia event.
 4. The method of claim 1,wherein delivering neural stimulation to elicit a sympathetic responseis responsive to the detected supraventricular arrhythmia event and isfurther responsive to at least one additional enabling condition.
 5. Themethod of claim 4, wherein the at least one additional enablingcondition includes a clock signal representative of a time range of aday, and the neural stimulation is enabled within the time range.
 6. Themethod of claim 4, wherein the at least one additional enablingcondition includes an activity signal representative of detectedactivity and the neural stimulation is enabled tithe detected activityis below an activity threshold.
 7. The method of claim 1, whereindelivering neural stimulation to elicit a sympathetic response includesstimulating sympathetic activity in a neural target.
 8. The method ofclaim 7, wherein stimulating sympathetic activity in a neural targetincludes stimulating neural activity in a stellate ganglion.
 9. Themethod of claim 7, wherein stimulating sympathetic activity in a neuraltarget includes stimulating neural activity in a cardiac sympatheticnerve.
 10. The method of claim 1, wherein delivering neural stimulationto elicit a sympathetic response includes inhibiting parasympatheticactivity in a neural target.
 11. The method of claim 8, whereininhibiting parasympathetic activity in a neural target includesinhibiting activity in a vagus nerve or a branch thereof.
 12. The methodof claim 8, wherein inhibiting parasympathetic activity in a neuraltarget includes inhibiting neural activity from baroreceptors or cardiacfat pads.
 13. The method of claim 1, wherein delivering neuralstimulation to elicit a sympathetic response includes transvascularlystimulating a neural target using an electric stimulation signaldelivering through at least one intravascularly-positioned electrode.14. The method of claim 1, wherein delivering neural stimulation toelicit a sympathetic response includes stimulating a neural target usingan electric stimulation signal delivered through at least one electrodein a nerve cuff.
 15. The method of claim 1, wherein delivering atreatment in response to a detected supraventricular arrhythmia eventfurther includes delivering antitachycardia pacing, delivering anantitachycardia shock, or delivering a drug therapy.
 16. A method,comprising: detecting a supraventricular arrhythmia event; anddelivering a closed-loop supraventricular arrhythmia treatment inresponse to a detected supraventricular arrhythmia event, including:delivering neural stimulation to elicit a sympathetic response; sensinga physiological response to the delivered neural stimulation; andadjusting the neural stimulation based on the sensed physiologicalresponse.
 17. The method of claim 16, wherein: sensing a physiologicalresponse to the neural stimulation includes sensing the physiologicalresponse using a physiologic sensor distinct from that detecting thesupraventricular arrhythmia event; and adjusting the neural stimulationdelivery scheme includes comparing the sensed physiologic sensorresponse to a target range for the sensed physiologic response andaltering a stimulation schedule, a duration, a duty cycle, or astimulation intensity of the neural stimulation based on the comparison.18. The method of claim 17, wherein sensing the physiological responseincludes sensing a blood pressure response, and adjusting the neuralstimulation includes adjusting the neural stimulation based on thesensed blood pressure response.
 19. The method of claim 17, whereinsensing the physiological response includes sensing a respirationresponse to stimulation of the neural target, and adjusting the neuralstimulation includes adjusting the neural stimulation based on thesensed respiration response.
 20. The method of claim 17, wherein sensingthe physiological response includes sensing nerve traffic.